 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.resources;

 import org.eclipse.core.runtime.IPath;

 /**
  * A context for workspace <code>save</code> operations.
  * <p>
  * Note that <code>IWorkspace.save</code> uses a
  * different save context for each registered participant,
  * allowing each to declare whether they have actively
  * participated and decide whether to receive a resource
  * delta on reactivation.
  * </p>
  * <p>
  * This interface is not intended to be implemented by clients.
  * </p>
  *
  * @see IWorkspace#save(boolean, org.eclipse.core.runtime.IProgressMonitor)
  */
 public interface ISaveContext {

     /*====================================================================
      * Constants related to save kind
      *====================================================================*/

     /**
      * Type constant which identifies a full save.
      *
      * @see ISaveContext#getKind()
      */
     public static final int FULL_SAVE = 1;

     /**
      * Type constant which identifies a snapshot.
      *
      * @see ISaveContext#getKind()
      */
     public static final int SNAPSHOT = 2;

     /**
      * Type constant which identifies a project save.
      *
      * @see ISaveContext#getKind()
      */
     public static final int PROJECT_SAVE = 3;

     /**
      * Returns current files mapped with the <code>ISaveContext.map</code>
      * facility or an empty array if there are no mapped files.
      *
      * @return the files currently mapped by the participant
      *
      * @see #map(IPath, IPath)
      */
     public IPath[] getFiles();

     /**
      * Returns the type of this save. The types can be:
      * <ul>
      * <li> <code>ISaveContext.FULL_SAVE</code></li>
      * <li> <code>ISaveContext.SNAPSHOT</code></li>
      * <li> <code>ISaveContext.PROJECT_SAVE</code></li>
      * </ul>
      *
      * @return the type of the current save
      */
     public int getKind();

     /**
      * Returns the number for the previous save in
      * which the plug-in actively participated, or <code>0</code>
      * if the plug-in has never actively participated in a save before.
      * <p>
      * In the event of an unsuccessful save, this is the value to
      * <code>rollback</code> to.
      * </p>
      *
      * @return the previous save number if positive, or <code>0</code>
      * if never saved before
      * @see ISaveParticipant#rollback(ISaveContext)
      */
     public int getPreviousSaveNumber();

     /**
      * If the current save is a project save, this method returns the project
      * being saved.
      *
      * @return the project being saved or <code>null</code> if this is not
      * project save
      *
      * @see #getKind()
      */
     public IProject getProject();

     /**
      * Returns the number for this save. This number is
      * guaranteed to be <code>1</code> more than the
      * previous save number.
      * <p>
      * This is the value to use when, for example, creating files
      * in which a participant will save its data.
      * </p>
      *
      * @return the save number
      * @see ISaveParticipant#saving(ISaveContext)
      */
     public int getSaveNumber();

     /**
      * Returns the current location for the given file or
      * <code>null</code> if none.
      *
      * @return the location of a given file or <code>null</code>
      * @see #map(IPath, IPath)
      * @see ISavedState#lookup(IPath)
      */
     public IPath lookup(IPath file);

     /**
      * Maps the given plug-in file to its real location. This method is intended to be used
      * with <code>ISaveContext.getSaveNumber()</code> to map plug-in configuration
      * file names to real locations.
      * <p>
      * For example, assume a plug-in has a configuration file named "config.properties".
      * The map facility can be used to map that logical name onto a real
      * name which is specific to a particular save (e.g., 10.config.properties,
      * where 10 is the current save number). The paths specified here should
      * always be relative to the plug-in state location for the plug-in saving the state.
      * </p>
      * <p>
      * Each save participant must manage the deletion of its old state files. Old state files
      * can be discovered using <code>getPreviousSaveNumber</code> or by using
      * <code>getFiles</code> to discover the current files and comparing that to the
      * list of files on disk.
      * </p>
      * @param file the logical name of the participant's data file
      * @param location the real (i.e., filesystem) name by which the file should be known
      * for this save, or <code>null</code> to remove the entry
      * @see #lookup(IPath)
      * @see #getSaveNumber()
      * @see #needSaveNumber()
      * @see ISavedState#lookup(IPath)
      */
     public void map(IPath file, IPath location);

     /**
      * Indicates that the saved workspace tree should be remembered so that a delta
      * will be available in a subsequent session when the plug-in re-registers
      * to participate in saves. If this method is not called, no resource delta will
      * be made available. This facility is not available for marker deltas.
      * Plug-ins must assume that all markers may have changed when they are activated.
      * <p>
      * Note that this is orthogonal to <code>needSaveNumber</code>. That is,
      * one can ask for a delta regardless of whether or not one is an active participant.
      * </p>
      * <p>
      * Note that deltas are not guaranteed to be saved even if saving is requested.
      * Deltas cannot be supplied where the previous state is too old or has become invalid.
      * </p>
      * <p>
      * This method is only valid for full saves. It is ignored during snapshots
      * or project saves.
      * </p>
      *
      * @see IWorkspace#addSaveParticipant(org.eclipse.core.runtime.Plugin, ISaveParticipant)
      * @see ISavedState#processResourceChangeEvents(IResourceChangeListener)
      */
     public void needDelta();

     /**
      * Indicates that this participant has actively participated in this save.
      * If the save is successful, the current save number will be remembered;
      * this save number will be the previous save number for subsequent saves
      * until the participant again actively participates.
      * <p>
      * If this method is not called, the plug-in is not deemed to be an active
      * participant in this save.
      * </p>
      * <p>
      * Note that this is orthogonal to <code>needDelta</code>. That is,
      * one can be an active participant whether or not one asks for a delta.
      * </p>
      *
      * @see IWorkspace#addSaveParticipant(org.eclipse.core.runtime.Plugin, ISaveParticipant)
      * @see ISavedState#getSaveNumber()
      */
     public void needSaveNumber();
 }

